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31.
Synthesis and properties of fluorescent light‐emitting polyamide hybrids with reactive nanosilica by epoxide functionalization 下载免费PDF全文
A series of poly(carbazole‐quinoxaline‐amide)s (PCQAs) containing phenyl and long alkyl chain as pendants was synthesized from polycondensation between a new diamine with a synthesized and several commercial dicarboxylic acids using Yamazaki's method. PCQAs had inherent viscosities and weight average molecular weights ( ) in the range of 0.48–0.62 dL g?1 and 51,600–58,500 g mol?1, respectively. These luminescent polymers are readily soluble in a variety of organic solvents and formed low‐colored and tough thin films. In this study, silane modified SiO2 (mSiO2) nanoparticles were prepared, characterized and used with PCQAs in preparation of nanocomposites via solution blending method. The interfacial interaction strength between mSiO2 and the polymer–matrix enhanced thermal stability (T10%, from 463°C to 500°C) and mechanical strength (from 100 MPa to 150 MPa) for composite containing 30 wt % mSiO2 in comparison with the pure polyamide. These materials showed good ability for extraction–elimination of metal ions such as Cr6+, Cr3+, Co2+, Zn2+, Pb2+, Cd2+, and Hg2+ from aqueous solutions either individually or in the mixture at various pH. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40219. 相似文献
32.
Hajar Jamshidian Seyyedhadi Khatami Azadeh Mogharei Farzaneh Vahabzadeha Arvin Nickzad 《Korean Journal of Chemical Engineering》2013,30(11):2052-2058
Ralstonia eutropha was able to degrade p-nitrophenol (PNP) at concentrations ranging from 5 to 15mg l ?1 in the presence of phenol which was kept at the constant concentration of 200 mg l ?1. More than 90% of phenol was degraded within 30 h and in the absence of PNP. While in this time period and in the presence of 15 mg l ?1 less than 30% of phenol was degraded and PNP removal ability of the test bacterium was about 20%. Kissiris as a natural source of silicon dioxide having a very rigid structure with many micropores irregularly distributed throughout its surface was used to evaluate effectiveness of the cell immobilization using a Kissiris-immobilized cell bioreactor [ICB]. By applying phenol-feeding regime in the ICB operated in a batch recycling mode, simultaneous degradation of phenol in total amount of 1,000 mg l ?1 with 15 mg l ?1 PNP was achieved within 40 h. 相似文献
33.
The mechanical property is a crucial factor in the design of bone tissue engineering scaffolds. In the current study, novel PLLA (Poly-L-lactic acid)–Hydroxyapatite (HA)–yttria-stabilized zirconia (YSZ) nanocomposite scaffold with various compositions was prepared and characterized. The effect of HA and YSZ contents on the mechanical behavior of the resultant composites was investigated. TEM micrograph revealed that HA particles are needle-like in shape and nano in size. Scanning electron microscopy (SEM) micrograph also showed that YSZ powder is in granule form and submicron size. SEM disclosed that all scaffolds had a highly interconnected porous structure and X-ray diffractometry revealed that there were some molecular interactions between PLA (Polylactic acid), HA, and YSZ in the composites. The results depicted that introducing YSZ to the nanocomposite leads to a significant increase in compressive strength, modulus, and densification strain. In addition, flexural strength and modulus showed an upward trend by adding YSZ particles to scaffolds. It should be noted that PLA–20%HA–20%YSZ indicates the highest strength and modulus in both compression and bending tests, though, it did not demonstrate the proper strain compared to other scaffolds. Thus, PLA–15%HA–15%YSZ has been reported as the best candidate due to appropriate strength and strain. Also, energy absorption in nanocomposites showed an upward trend by increasing the amount of YSZ particles. It was found that the strength of samples was declined after being soaked in simulated body fluid. However, scaffolds with HA underwent more decrease in strength compared to samples containing YSZ. 相似文献
34.
Majid Kermani Masoud Farzaneh László E. Kollár 《Journal of Wind Engineering & Industrial Aerodynamics》2010,98(10-11):592-599
Aeolian vibration in bare and iced cable was simulated using the theory of cable vibration. High frequency vibration creates stresses in the cable and consequently in the ice covering that cable, which may result in ice failure and eventually ice shedding. These stresses were estimated in this study. Displacement of the cable during vibration was determined; furthermore, instantaneous wind loads in vertical and transverse directions, additional stresses induced by the motion in the cable and in the atmospheric ice, as well as torque due to cable springback were calculated. In order to simulate the loading conditions of a chunk of atmospheric ice in the middle of a span, a new model was developed using ABAQUS. Results from this model show in spite of high frequency vibration, the resulting level of stress in atmospheric ice is far less than its failure limit. In other words, the atmospheric ice under the condition assumed in this investigation does not shed due to aeolian vibration. 相似文献
35.
Various lines of atomic fluorine laser have been studied over a wide pressure range for determination of the relative intensity of each pressure-dependent line. In this investigation, the most probable laser pumping mechanisms have been verified. 相似文献
36.
Jaleh Mansouri Chris A. Wood Katherine Roberts Yi-Bing Cheng Robert P. Burford 《Journal of Materials Science》2007,42(15):6046-6055
Glass frits were added into silicone-based composites with the aim to improve low temperature ceramification at elevated temperatures.
The effect of glass frits on the properties of ceramic residue is investigated. Field emission scanning electron microscopy
(FESEM), electron probe microchemical analysis (EPMA) and X-ray diffraction analysis (XRD) showed that glass frits reacted
via a eutectic reaction with mica and silica. Electrical conductivity measurements at elevated temperatures showed a decline
in volume resistivity with glass frit addition. It was concluded that increased conductivity is a result of ionic conduction
of the glass phase produced by eutectic reactions between frits, silica and mica at high temperatures. Thermal mechanical
analysis (TMA) was used to explore the dimensional changes of these composites during programmed heat treatment. 相似文献
37.
M. Farzaneh I. Fofana H. Hemmatjou 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(1):185-193
Several major parameters affecting the electrical behavior of natural snow, namely volume conductivity and density, liquid water content and conductivity of water melted from snow, are crucial for the characterization of the electrical performance of snow-covered HV insulators. However, little study has been devoted to this subject, despite of its importance. These parameters are found to vary significantly with snow composition and purity as well as with other parameters, such as temperature, airborne pollutants, electric field strength and polarity. From laboratory experiments carried out on a large number of snow samples, it was found that DC conductivity of snow shows a peak at about -2degC. This apparently curious behavior near the melting temperature is attributed to important changes to the microstructure of snow. A correlation between DC conductivity and snow temperature was established 相似文献
38.
In this study, effect of plasma pretreatment on the absorption of carboxilated carbon nanotubes (CNTs) on the surface of cotton fabrics was investigated. Treated samples were characterised using a Raman spectrophotometer. Also, the morphological properties of samples were studied using a scanning electron microscope. Electrical resistance and interactions between CNTs and plasma-treated cotton functional groups at the surface were also evaluated. Antibacterial activity of cotton fabric when modified by low temperature plasma and stabilised with CNTs was also investigated. Results showed a uniform coating of CNTs on the plasma-treated cotton fabric and it was found that the plasma treatment is effective on improving CNTs absorption by cotton fabric. Generally, cotton fabric characterisation, such as antibacterial activity and electrical conductivity, after plasma treatment and loading CNT are improved. 相似文献
39.
Elnaz Miandoabchi Farzaneh Daneshzand W.Y. Szeto Reza Zanjirani Farahani 《Computers & Operations Research》2013
This paper addresses the problem of designing urban road networks in a multi-objective decision making framework. Given a base network with only two-way links, and the candidate lane addition and link construction projects, the problem is to find the optimal combination of one-way and two-way links, the optimal selection of network capacity expansion projects, and the optimal lane allocations on two-way links to optimize the reserve capacity of the network, and two new travel time related performance measures. The problem is considered in two variations; in the first scenario, two-way links may have different numbers of lanes in each direction and in the second scenario, two-way links must have equal number of lanes in each direction. The proposed variations are formulated as mixed-integer programming problems with equilibrium constraints. A hybrid genetic algorithm, an evolutionary simulated annealing, and a hybrid artificial bee colony algorithm are proposed to solve these two new problems. A new measure is also proposed to evaluate the effectiveness of the three algorithms. Computational results for both problems are presented. 相似文献
40.
Atabak Nejadfard M. J. Yazdanpanah Iraj Hassanzadeh 《Neural computing & applications》2013,22(2):337-347
Double inverted pendulum on a cart (DIPC) is a highly nonlinear system. Due to its complex dynamics, it is widely used as a test-bed plant for the verification of newly designed controllers. In DIPC, two pendulums are kept upward by linear movements of cart. Because of this linear motions and frequent switching of velocity directions, another nonlinearity caused by friction becomes dominant around the equilibrium point. Friction introduces limit cycles to the system and results in a poor steady-state response. To eliminate these negative effects, the locally linear neuro-fuzzy (LLNF) approach is used to build an inverse model for friction compensation. This model is compared with multilayer perceptron network in order to demonstrate the better performance of LLNF. To stabilize DIPC, a common optimal controller is used, and despite its limited performance, experimental results show that the application of inverse modeling for friction compensation improves the steady-state response outstandingly. 相似文献